Recording needle and method of making the same



1965 KAEMON osuRA ETAL 3,216,730

RECORDING NEEDLE AND METHOD OF MAKING THE SAME Filed Nov. 21. 1960 INVENTORS KAEMON OGURA ZMDYOSHCSORO Ocwmz BY 7% ZIMFM ATTORNEY5 United States Patent 3,216,730 RECORDING NEEDLE AND METHOD OF MAKING THE SAME Kaemon Ogura and Yoshigoro Ogura, Tokyo, Japan, assignors of one-fifth each to Seishiro Ogura, Junshiro Ogura, and Shunzaburo Ogura, all of Tokyo, Japan Filed Nov. 21, 1960, Ser. No. 70,540 Claims. (Cl. 274-38) The present invention relates to a recording needle and particularly the method of manufacturing the same.

An object of the invention is to provide a simplified method of preparing a recording needle. A still further object of the invention is to provide a method of manufacturing a recording needle wherein the diamond microparticle is soldered to the needle and thereafter is ground to proper shape.

A still further object of the invention is to provide a recording needle wherein the diamond particle is securely attached to the metallic stem.

With the above and other objects in view which will become apparent from the detailed description below some preferred forms of the invention are shown in the drawings in which:

FIG. 1 is a cross sectional view with a portion in elevation of the top of a recording needle illustrating the usual way of manufacturing such needle;

FIG. 2 is an eelvational view of a complete recording needle manufactured by the process of this invention;

FIG. 3 is a cross sectional view with a portion in elevation of the top of a needle showing one modification;

FIG. 4 is a similar View illustrating another modification;

FIG. 5 is a similar view illustrating a still further modification;

FIG. 6 is a view illustrating an intermediate stage in the manufacture of the invention shown in FIG. 3, and

FIG. 7 is a similar view to FIG. 6 in its manufacture of the invention shown in FIG. 4.

In the drawings similar reference characters indicate like parts.

Referring to FIG. 1 which illustrates the usual method now employed in manufacturing recording needles a slot 10 is first bored in the top of the metallic stem 11 of the needle. Then a rectangular diamond particle 12 is inserted in the slot 10 and secured to the stem 11 by means of the adhesive 14. The particle 12 then has the rectangular edges removed at the top thereof so as to form the rounded conical slopes 15. This method requires the troublesome procedure of boring the slot 10 into the head of the stem 11, grinding the diamond particle 12 first to a rectangular form, then securing the rectangular diamond particle 12 to the stem by means of the adhesive 14 and thereafter grinding the top thereof to the conical formation shown at 15. Since the diamond particle 12 is secured to the stem 11 by the adhesive 14 alone it naturally results that the diamond particle 12 may be easily dislocated.

In one embodiment of the present invention, a diamond particle 16 is first coated with mercury in the same way as the back of a mirror. This portion of the step may be termed mercury plating or lapping. In FIG. 3 which illustrates this method, mercury lapping as indicated at 17. Thereafter the diamond particle may be easily soldered to the top of the needle stem 11.

Since the diamond particle is directly mercury plated 3,216,730 Patented Nov. 9, 1965 or lapped, then soldered to the top of the metal needle, the mercury lapped surface rigidly adheres to the metal stem 11 and the diamond particle can not be easily dislocated. The diamond may then be ground into cone shape as shown in FIG. 3. There is no need to bore the needle as shown in FIG. 1 nor is there any necessity for manufacturing the diamond particle so as to have a rectangular form. Moreover since the small diamond particles may be used without any processing, the cost of such crushed diamonds is far lower than in the case required by the conventional method shown in FIG. 1 and therefore the products may be sold at low prices.

In another embodiment of the present invention, a diamond particle 16 is similarly coated with mercury in the similar way as the back of a mirror and in addition, prior to soldering step of the diamond to stem 11, mercury lapped diamond is metallically plated with copper or nickel or resembling metal as indicated at 18 in FIG. 4. Thereafter this diamond particle may be easily soldered to the top of the needle stem 11 as shown at 19. Subsequent process thereto has been described in the first embodiment.

In the third embodiment of the present invention, a diamond particle 16 is directly plated metallically with copper or nickel or resembling metal as indicated at 18 in FIG. 5. Thereafter this diamond particle may be easily soldered to the top of the needle stem 11. Thereafter, the soldered stem is treated as the other embodiments already described. In FIGS. 3, 4 and 5, the top of the metallic stem is plane. This may be made are shaped for convenience of soldering as shown in FIG. 6.

It is thought that the invention and its advantages will be understood from the foregoing description and it is apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing its material advantages, the forms hereinbefore described and illustrated in the drawing being merely preferred embodiments thereof.

We claim:

1. A diamond recording needle comprising a needle stem having a flat top extending at right angles to the longitudinal axis of said stem and a mercury plated diamond particle soldered to the top of said needle stem, said diamond particle having a point at the side away from said stern, and a metallic layer of nickel interposed between said mercury plated diamond particle and the solder.

2. A diamond recording needle comprising a needle stem having a flat top extending at right angles to the longitudinal axis of said stem and a mercury plated diamond particle soldered to the top of said needle stern, said diamond particle having a point at the side away from said stem, and a metallic layer of copper is located between said mercury plated diamond particle and the solder.

3. A method of manufacturing a recording needle comprising mercury plating a diamond particle, then applying a second metallic plating to said diamond particle, then soldering the same to the flat top of a metallic stem and finally grinding said particle to the shape of a needle.

4. A method as set forth in claim 3 where said metallic plating is with nickel.

5. A method as set forth in claim 3 wherein said metallic plating is copper.

(References on following page) 3 References Cited by the Examiner OTHER REFERENCES UNITED STATES PATENTS 2glalnnon, American Machinist, Aug. 29, 1946, pages 31. 2 52 1 Handbook of Chemistry and Physics, 39th edition, pub- 2:961i750 11/60 Bender 5 lished by Chemical Rubber Publishing Co., 1958, page 3,110,089 11/63 Hill 29-s02 FOREIGN PATENTS NORTON ANSHER, Primary Examiner.

306,157 5/30 Great Britain. 10 STEPHEN W. CAPELLI, A. GUIDA, EMIL G. 557,117 11/43 Great Britain. ANDERSON, Examiners. 

1. A DIAMOND RECORDING NEEDLE COMPRISING A NEEDLE STEM HAVING A FLAT TOP EXTENDING AT RIGHT ANGLES TO THE LONGITUDINAL AXIS OF SAID STEM AND A MERCURY PLATED DIAMOND PARTICLE SOLDERED TO THE TOP OF SAID NEEDLE STEM, SAID DIAMOND PARTICLE HAVING A POINT AT THE SIDE AWAY FROM SAID STEM, AND A METALLIC LAYER OF NICKEL INTERPOSED BETWEEN SAID MERCURY PLATED DIAMOND PARTICLE AND THE SOLDER. 